#include <bits/stdc++.h>

#define FOR(n, a, b) for(int n = (a); n < (b); ++n)
#define ALL(x) x.begin(), x.end()
#define pb push_back
#define st first
#define nd second

using namespace std;

typedef long long ll;
typedef pair<int, int> pint;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pint> vii;
typedef tuple<int, int, int> ti;
typedef vector<ti> vti;

int n;
vector<tuple<int, int, int>> pts;
vvi g;
vi dfsord;
vi parent;
map<int, ti> asgn;

inline ll xdif(ti x1, ti x2) {
    return get<0>(x2) - get<0>(x1);
}

inline ll ydif(ti x1, ti x2) {
    return get<1>(x2) - get<1>(x1);
}


void dfsinit(int v, int p) {
    for(int n : g[v]) {
        if(n == p) continue;
        parent[n] = v;
        dfsord.pb(n);
        dfsinit(n, v);
    }
}

inline double k(double x) { return x * x; }

ti get_next(ti from) {
    sort(pts.begin(), pts.end(), [&from](ti t1, ti t2) {
        return xdif(from, t1) * ydif(from, t2) > xdif(from, t2) * ydif(from, t1);
    });

    /*for(auto x : pts) {
        cout << "(" << get<0>(x) << ", " << get<1>(x) << "), ";
    } cout << endl;*/

    return pts.back();
}

void assign_numbers(int k) {
    for(int n : g[k]) {
        if(n == parent[k]) continue;
        ti x = get_next(asgn[k]);
        pts.pop_back();
        asgn[n] = x;
        assign_numbers(n);
    }

}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    parent.resize(n);
    g.resize(n);
    int x, y;
    /*for(int i = 0; i < n - 1; i++) {
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
    }*/

    for(int i = 0; i < n; i++) {
        cin >> x >> y;
        pts.pb({x, y, i});
    }

    sort(pts.begin(), pts.end());
    ti root = pts.back();
    pts.pop_back();
    asgn[0] = root;

  //  dfsord.pb(0);
  //  dfsinit(0, -1);
    parent[0] = -1;

    //ti st = {0, 10, 0};
    //get_next(st);
    assign_numbers(0);

    for(int i = 0; i < n; i++) {
        for(int j : g[i]) {
            if(j < i) continue;
            cout << get<2>(asgn[i]) << ' ' << get<2>(asgn[j]) << '\n';
        }

    }

    return 0;
}